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| 1 | Particle-size-dependent upconversion luminescence of NaYF4:Yb,Er nanoparticles in organic solvents and water at different excitation power densities显示文摘A systematic study of the luminescence properties of monodisperse β-NaYF4: 20%Yb^3+,2%Er^3+ upconversion nanoparticles (UCNPs)with sizes ranging from 12--43nm is presented utilizing steady-state and time-resolved fluorometry. Special emphasis was dedicated to the absolute quantification of size-and environment-induced quenching of upconversion luminescence (UCL)by highenergy O-H and C-H vibrations from solvent and ligand molecules at different excitation power densities (P).In this context,the still-debated population pathways of the 4F9/2 energy level of Er^3+ were examined.Our results highlight the potential of particle size and P value for color tuning based on the pronounced near-infrared emission of 12nm UCNPs,which outweighs the red Er^3+emission under 'strongly quenched'conditions and accounts for over 50% of total UCL in water.Because current rate equation models do not include such emissions,the suitability of these models for accurately simulating all (de)population pathways of small UCNPs must be critically assessed.Furthermore,we postulate population pathways for the 4F9/2energy level of Er3.,Which correlate with the size-,environment-,and P-dependent quenching states of the higher Er^3+ energy levels. | Marco Kraft Christian Würth Verena Muhr Thomas Hirsch Ute Resch-Genger | 2018 | Nano Research2018，11，12： | 8 |
| 2 | Multiband emission from single β-NaYF_(4)(Yb,Er) nanoparticles at high excitation power densities and comparison to ensemble studies显示文摘Ensemble and single particle studies of the excitation power density (P)-dependent upconversion luminescence (UCL) of core and core-shell β-NaYF_(4):Yb,Er upconversion nanoparticles (UCNPs) doped with 20% Yb^(3+) and 1% or 3% Er^(^(3+)) performed over a P regime of 6 orders of magnitude reveal an increasing contribution of the emission from high energy Er^(3+) levels at P > 1 kW/cm^(2). This changes the overall emission color from initially green over yellow to white. While initially the green and with increasing P the red emission dominate in ensemble measurements at P < 1 kW/cm^(2), the increasing population of higher Er^(^(3+)) energy levels by multiphotonic processes at higher P in single particle studies results in a multitude of emission bands in the ultraviolet/visible/near infrared (UV/vis/NIR) accompanied by a decreased contribution of the red luminescence. Based upon a thorough analysis of the P-dependence of UCL, the emission bands activated at high P were grouped and assigned to 2–3, 3–4, and 4 photonic processes involving energy transfer (ET), excited-state absorption (ESA), cross-relaxation (CR), back energy transfer (BET), and non-radiative relaxation processes (nRP). This underlines the P-tunability of UCNP brightness and color and highlights the potential of P-dependent measurements for mechanistic studies required to manifest the population pathways of the different Er^(3+) levels. | Florian Frenzel Christian Würth Oleksii Dukhno Frédéric Przybilla Lisa MWiesholler Verena Muhr Thomas Hirsch Yves Mély Ute Resch-Genger | 2021 | Nano Research2021，14，11： | 3 |
| 3 | AMP-activated protein kinase and metabolic regulation in cold-hardy insects 显示文摘 | RIDER M H HUSSAIN N DILWO- RTH S M | 2011 | Journal of Insect Physiology2011，57，11： | 1 |
| 4 | An enormousamorphous silica stock in boreal wetlands显示文摘 | Struyf E M?rth CM Humborg C Conley DJ | 2010 | Journal ofGeophysical Research2010，115，04： | 1 |
| 5 | A posteriori error estimators for the Stokes equations显示文摘 | R. Verfürth | 1989 | Numerische Mathematik1989，，3： | 1 |
| 6 | CO2supersaturation along the aquatic conduit in Swedish watersheds as constrained by terrestrial respiration,aquatic respiration and weathering显示文摘 | Humborg C Mrth C-M Sundbom M | 2010 | Global Change Biology2010，16，： | 1 |
| 7 | Eculizumab,a terminal complement inhibitor,improves anaemia in patients with paroxysmal nocturnal haemoglobinuria显示文摘 | Schubert J Hillmen P Rth A | 2008 | Br J Haematol2008，142，2： | 1 |
| 8 | Effect of aglutathione S-transferase inhibitor on oxidative stress andischemia reperfusion induced apoptotic signalling of culturedcardiomyocytes显示文摘 | Rth E Marczin N Balatonyi B | 2011 | Exp Clin Cardiol2011，16，3： | 1 |
| 9 | Differential basolateral–apical distribution of scavenger receptor, class B, type I in cultured cells and the liver显示文摘 | Stefanie Fruhwürth Werner J. Kovacs Robert Bittman Simon Messner Clemens R?hrl Herbert Stangl | 2014 | Histochemistry and Cell Biology2014，，： | 1 |
| 10 | Reasoning by Coordination:An Integration of Case-based and Rule-based Reasoning Systems显示文摘 | RTH Chi Kiang M Y | 1993 | Knowledge-based Systems1993，6，2： | 1 |
| 11 | Iron isotope variations in Holocene sediments of the Gotland Deep,Baltic Sea显示文摘 | Fehr M A Andersson P S Hálenius U M(o)rth C-M | 2008 | Geochim Cosmochim Acta2008，72，3： | 1 |
| 12 | A novel geochemical approach to paleorecords of dust deposition and effective humidity: 8500 years of peat accumulation at Store Mosse (the “Great Bog”), Sweden显示文摘 | Malin E. Kylander Richard Bindler Antonio Martínez Cortizas Kerry Gallagher Carl-Magnus M?rth Sebastien Rauch | 2013 | Quaternary Science Reviews2013，，： | 1 |
| 13 | Brainderived neurotrophic factor promotes axonal regeneration and long-term survival of adult rat spinal motoneurons in vivo显示文摘 | NOVIKOV L NOVIKOVA L KE LLE RTH JO | 1997 | Neuroscience1997，79，3： | 1 |
| 14 | Arctic Ocean manganese contents and sediment color cycles 显示文摘 | Lowemark L Jakobsson M M rth M | 2008 | Polar Re- search2008，27，： | 1 |
| 15 | Landing pattern and vertical loading rates during first attempt of barefoot running in habitual shod runners显示文摘 | Cheung RTH Rainbow MJ | | 0，，： | 1 |
| 16 | Volume and surface effects on two-photonic and three-photonic processes in dry co-doped upconversion nanocrystals显示文摘Despite considerable advances in synthesizing high-quality core/shell upconversion(UC)nanocrystals(NC;UCNC)and UCNC photophysics,the application of near-infrared(NIR)-excitable lanthanide-doped UCNC in the life and material sciences is still hampered by the relatively low upconversion luminescence(UCL)of UCNC of small size or thin protecting shell.To obtain deeper insights into energy transfer and surface quenching processes involving Yb^(3+) and Er^(3+) ions,we examined energy loss processes in differently sized solid core NaYF_(4) nanocrystals doped with either Yb^(3+)(YbNC;20%Yb^(3+))or Er^(3+)(ErNC;2%Er^(3+))and co-doped with Yb^(3+) and Er^(3+)(YbErNC;20%Yb^(3+) and 2%Er^(3+))without a surface protection shell and coated with a thin and a thick NaYF_(4) shell in comparison to single and co-doped bulk materials.Luminescence studies at 375 nm excitation demonstrate back-energy transfer(BET)from the ^(4)G_(11/2) state of Er^(3+) to the ^(2)F_(5/2) state of Yb^(3+),through which the red Er^(3+) ^(4)F_(9/2) state is efficiently populated.Excitation power density(P)-dependent steady state and time-resolved photoluminescence measurements at different excitation and emission wavelengths enable to separate surface-related and volume-related effects for two-photonic and three-photonic processes involved in UCL and indicate a different influence of surface passivation on the green and red Er3+emission.The intensity and lifetime of the latter respond particularly to an increase in volume of the active UCNC core.We provide a three-dimensional random walk model to describe these effects that can be used in the future to predict the UCL behavior of UCNC. | Bettina Grauel Christian Würth Christian Homann Lisa Krukewitt Elina Andresen Janina Roik Sebastian Recknagel Markus Haase Ute Resch-Genger | 2022 | Nano Research2022，15，3： | 1 |
| 17 | A posteriori error estimators for the Stokes equations显示文摘 | R. Verfürth | 1989 | Numerische Mathematik1989，，3： | 1 |
| 18 | A review of a posteriori error estimates for nonlinear problems, Lr-estimate for finite element discretization of elliptic equations显示文摘 | Verfürth R | 1998 | Math Comp1998，67，224： | 1 |
| 19 | Arctic Ocean manganese contents and sediment colour cycles显示文摘 | L?wemark L Jakobsson M M?rth M | 2008 | Polar Research2008，27，2： | 1 |
| 20 | Single-agent versus combination chemotherapy as first-line treatment for patients with advanced non-small cell lung cancer and performance status 2: A literature-based meta-analysis of randomized studies显示文摘 | Charlott M?rth Antonis Valachis | 2014 | Lung Cancer2014，，： | 1 |
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